Melanocyte colonization of adenocarcinoma arising in an ovarian dermoid

An adenocarcinoma which arose in a dermoid cyst of the ovary displayed areas of melanocyte colonization and pigmentation. Ultrastructural study revealed the presence of epithelial tumour cells and melanocytes; many tumour cells contained compound melanosomes, but not premelanosomes, suggesting transfer of melanin from melanocytes to tumour cells. Melanocyte colonization of malignant tumours is a curious phenomenon the significance of which remains to be elucidated.